Coped mortice and tenons with router

[siggy_7]

I'm building up to making a pair of glazed doors for my garage. Material will be cedar, each door will be about 1.1m wide and 2.2m tall. The joints for such a door around the glazing at the top looked rather more complicated than anything I have attempted before, so I thought I'd give myself a trial run yesterday.

The results are a real disaster (so plenty of lessons learned and the right call for a practice!). No harm done. I now realise that my key mistake was not understanding the relationship between the coped scribe and the dimensions of the mortice and tenon - I hadn't lined up the height of the cope cutter to match the cheek of the tenon, so the mortice and tenon geometry was consequently all over the place. I also processed things in the wrong order, learned that lesson for next time.

The sequence I have arrived at for test number 2 is the following:

1. Start with representative thickness wood - my first test stock was 32mm which is too thin. I'm expecting to get about 42-44mm from the cedar I have for the doors when I plane it
2. First step is to cut the mortice and tenon to join the rails and stiles - have some questions on this
3. Then cut the cope in the rails, coping cutter height to just touch the cheek of the tenon. Some questions about fence position which I'll come back to
4. Cut the matching profile to the cope on all rails and stiles
5. Set the height of the glazing rebate to the top of the tenon cheek, then cut the glazing rebate on all parts.

My questions, which the articles I have read don't cover, are:

1. The coping of the rail affects how far the tenon will pass into the stile. I therefore need to cut the mortice deeper than the tenon made in point 2 above by the extra depth that this cut will provide?
2. The cutting of the glazing rebate on the rail will also slice off a bit of the tenon on the rail. I therefore need to cut the mortice narrower than the tenon made in point 2 on the glazing end by the width of the glazing rebate?
3. What determines the fence position setting for the coping cut? (This would appear to be related to the mortice and tenon geometry choices in question 1)

Any pointers on the above or other advice on making this joint gratefully received.

 

[siggy_7]

I had a go at test 2 today with much improved results, but still not quite what I was hoping for.

The overall frame looks ok, but the joints aren't quite right as you can see below:

I believe I am constrained by setting the scribe cutter so that the top is flush with one of the cheeks of the mortice and tenon joint in the corner. So therefore my conclusion looking at the above is that I didn't set the ovolo cutter to the right height after cutting the scribe on the ends of the rails. How is this reliably achieved in practice? Is there a knack to it or is it a case of just creeping up on what one determines to be a good fit?

 

[James-1986]

Is the whole door glazed? how thick is the glazing?

I cannot see a haunch on that joint, can you pull it apart and take a photo?

What are the dimensions of the rails and stiles on the finished door? At 1100mm wide I'd want a mid rail as well.

Good choice on the timber

 

[siggy_7]

James, the doors will be glazed at the top. The glazing will be double glazed for noise and heat, the glazing panels will be quite thin probably 16-18mm so quite a small gap between the panes. Something like this:

http://longman-gates.co.uk/made-to-measure-coleman-wooden-garage-doors.html

I will try and get the timber as thick as possible for this work. Looking at what I've got, I should get 42mm as a minimum but maybe a couple of mm more. The rails will be about 125mmm, I could make the stiles the same or maybe go narrower to about 100mm, not sure on the aesthetics. There will be a third rail at the bottom of the glazing, probably a 4th rail halfway between the bottom of the glazing and the bottom rail, and a diagonal bracing as well behind the panelled section. The lower rails and bracing will have to be thinner by the tongue and groove thickness, which will probably be about 14-16mm thick.

This is what the end of the rail looks like opened up:

 

[ColeyS1]

for two doors it'd probably be quicker to scribe by hand - and good practice

 

[dzj]

The rebate and mortice on the stile is offset by about 0.5mm.
A bit of tweaking will sort this out, so that they're flush when you lay them on a flat surface.

Maybe if you try referencing off the bottom instead the top.
Hard to say really, without seeing your whole setup.

 

[siggy_7]

The rebate and mortice on the stile is offset by about 0.5mm.
A bit of tweaking will sort this out, so that they're flush when you lay them on a flat surface.

I wondered whether I might have got the height set a bit wrong for the scribing cutter. I think I'm going to modify my order a bit more so that I cut the shorter tenon shoulders and cheeks first, then I have the face of the tenon to set the scribing cutter to.

Coley - you haven't seen my hand tool work! I guess it all comes down to what we enjoy and practice at, but I'm much happier and more confident setting up routers than making cuts precisely with hand tools. Hand tool work would seem to require a great deal of patience to learn and also a bit of craftmanship, both qualities I don't possess. But I have fun with my power tools, and I enjoy the precision and repeatability that they achieve. If it takes me longer to set up for a couple of cuts than someone practiced in using whatever tools would be necessary to achieve that scribing cut (and I genuinely wouldn't even know what hand tools to start with) then so be it, but it's quicker than me having 5 attempts by hand before completely losing my enthusiasm for the project.

 

[James-1986]

Can you not adjust the height of the cutter to create a quirk on the moulding? Having a feather edge on the end of the rail could give you a few headaches and might spoil the job. You could always just mould the top and mid rails, leave the stiles and make life easy for yourself!

 

[Steve Maskery]

I realise that this is not how you want to do it, but for the benefit of anyone else this is my 2p.

I know I have a reasonably high profile on here as a woodworking writer, but that does not mean I am an expert woodworker. I am not. No formal training, just 57 years of osmosis. I have very modest woodworking skills. I've made some nice pieces in the past, but I wouldn't tackle what you are planning. I like an easy life.

I'm planning to make a pair of double garage doors, too. I want them to look trad but without all that difficult machining. So this is what I plan to do.

1 Start with 62mm timber. This will finish at, say 55mm, which will give me enough thickness to put in 25mm insulation. It's not a lot, but better than nothing. I did consider 75mm, finishing at say 70, but that is one thick door. I might still do that.

2 Make the doors with double tenons (or is it twin? Side-by-side, anyway). It is immensely strong due to the large gluing area. I can do this tricky joint well, I'm the owner of a very good jig...
No rebates, just a plain rectangular door.

3 Glue glazing beads on to make rebates, like I have on my window frames for the workshop. It's much easier and looks the same when it is painted.
Install the glass and the vertical boarding.

4 Rout a rebate in both doors where they meet. Then attach a moulded cover strip. This way both doors can be identical.

Yes it is all cheating, but the end result i excellent an I'd rather do it this way well then the trad way and make a pig's ear of it.

Good on you for doing a practise run, very good idea.

S